Method of manufacturing a semiconductor device having an insulating protective film covering at least a portion of a tile-shaped element

ABSTRACT

The invention provides a semiconductor device, a method of manufacturing the same, an electro-optic device and an electronic apparatus which are capable of addressing or solving a problem of mechanical mounting of a semiconductor element chip on a substrate. A semiconductor device includes a tile-shaped microelement bonded to a substrate, and an insulating functional film provided to cover at least a portion of the tile-shaped microelement.

This is a Divisional of application Ser. No. 10/463,673 filed Jun. 18,2003, now U.S. Pat. No. 7,435,998. The disclosure of the priorapplication is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a semiconductor device, a method ofmanufacturing the same, an electro-optic device and an electronicapparatus.

2. Description of Related Art

In the related art, a gallium arsenide surface emitting laser (VCSEL), aphotodiode (PD) or a high electron mobility transistor (HEMT) isprovided on a silicon semiconductor substrate, and a micro silicontransistor is provided instead of a thin film transistor (TFT) for eachpixel of a liquid crystal display (LCD). In this way, various relatedart techniques can be used to form a semiconductor device on a substrateincluding a different material.

An example of such a semiconductor device including a semiconductorcomposed of a different material is an optoelectronics integratedcircuit (OEIC). The optoelectronics integrated circuit is an integratedcircuit including an optical input/output device in which an opticalsignal is used to input and output a signal from and to the outside,while an electric signal is used to process a signal.

SUMMARY OF THE INVENTION

In a computer, the operational speed (operational clock) in a CPU can beincreased due to the miniaturization of the internal structure of anintegrated circuit. However, the signal transfer speed of a bus isreaching a limit substantially, and thus the transfer speed becomes abottleneck of the processing speed of a computer. If signal transfer inthe bus can be performed by an optical signal, the limit of theprocessing speed of a computer can be significantly increased. In orderto realize this, a micro light-emitting element or light-receivingelement must be incorporated into an integrated circuit includingsilicon.

However, silicon is an indirect semiconductor and thus cannot emitlight. Therefore, silicon must be combined with a semiconductorlight-emitting element including a material other than silicon to forman integrated circuit.

A promising related art semiconductor light-emitting element is asurface emitting laser (VCSEL) including a compound semiconductor suchas gallium arsenide (GaAs) or the like. However, the surface emittinglaser does not have lattice matching with silicon, and it is thus verydifficult to form the surface emitting laser directly on a siliconintegrated circuit by a semiconductor process, such as epitaxy or thelike.

The surface emitting laser is generally formed on a gallium arsenidesubstrate. Therefore, in a conceivable related art method, the surfaceemitting laser on the gallium arsenide substrate is formed in a chip,and the chip is mechanically mounted on a silicon integrated circuitboard to combine together an electric signal transfer circuit and anoptical signal transfer circuit.

However, when a semiconductor light-emitting element such as a surfaceemitting laser chip or the like, or a semiconductor light-receivingelement, such as a photodiode or the like, is mechanically mounted on asilicon semiconductor substrate, there is a problem of reliability suchas the short lifetime of a semiconductor element. Therefore, it isnecessary to suppress the deterioration in function of the semiconductorelement in practical use.

Particularly, when the semiconductor light-emitting element orsemiconductor light-receiving element is used as the semiconductorelement, the optical properties of a film for covering the semiconductorelement and an adhesive to bond the film to the substrate must becontrolled to facilitate light emission and reception.

The present invention addresses the above and/or other considerations,and provides a semiconductor device, a method of manufacturing the same,an electro-optic device and an electronic apparatus. All of the abovecan be provided to address or solve the problem with mechanical mountingof a semiconductor device chip on a substrate.

In order to address or achieve the above, a semiconductor device of thepresent invention includes a tile-shaped microelement bonded to asubstrate, and an insulating functional film provided to cover at leasta portion of the tile-shaped microelement.

In the semiconductor device of the present invention, the function as anelectronic device or optical device can be imparted to the tile-shapedmicroelement to form a device having any desired function, and thesemiconductor device can be made compact (high density).

Since the insulating functional film is provided to cover at least aportion of the tile-shaped microelement, for example, the functionalfilm is given a barrier property against oxygen and moisture to suppressthe deterioration in the element function, thereby increasing thelifetime of the element. The tile-shaped microelement may include acompound semiconductor or a silicon semiconductor, and the substratehaving the tile-shaped microelement bonded thereto may be a siliconsemiconductor substrate or a compound semiconductor substrate.

In the semiconductor device, the functional film preferably covers thetile-shaped microelement in a sealed state.

In this case, particularly when the functional film is given the barrierproperty against oxygen and moisture, the deterioration of thetile-shaped microelement due to oxygen and moisture can be securelyreduced or prevented.

In the semiconductor device, the tile-shaped microelement is preferablya light emitting element, such as a surface emitting laser or lightemitting diode, or a light receiving element such as a photodiode or thelike.

In this case, when the tile-shaped microelement is mechanically mountedon, for example, a silicon integrated circuit board, an electric signaltransfer circuit and an optical signal transfer circuit can be combinedtogether.

In the semiconductor device, the functional film is preferablytransmissive to visible light and infrared light.

In this case, the functional film is provided corresponding to a lightemitting section or light receiving section of the tile-shapedmicroelement serving as the light-emitting element or light-receivingelement so that light emission from or reception by the tile-shapedmicroelement is not inhibited by the functional film.

In the semiconductor device, the functional film is preferablynon-transmissive to visible light and infrared light.

In this case, the functional film is provided on the side opposite tothe surface on which the light emitting section or light receivingsection of the tile-shaped microelement serving as the light-emittingelement or light-receiving element is formed, so that even when thetile-shaped microelement is thin and thus transmits light, thefunctional film can prevent a leakage of light transmitted through thetile-shaped microelement to the outside or reduce such leakage.

In the semiconductor device, the substrate is light-transmissive, andthe tile-shaped microelement is preferably bonded to thelight-transmissive substrate with an adhesive which is transmissive tovisible light and infrared light.

In this case, when the light emitting section or light receiving sectionis provided on the substrate side of the tile-shaped microelementserving as the light-emitting element or light-receiving element, lightemission from or reception by the tile-shaped microelement is notinhibited by the adhesive.

In the semiconductor device, the tile-shaped microelement is preferablybonded to the substrate with an adhesive which is non-transmissive tovisible light and infrared light.

In this case, the light emitting section or light receiving section isformed on the side opposite to the substrate side of the tile-shapedmicroelement serving as the light-emitting element or light-receivingelement so that even when the tile-shaped microelement is thin and thustransmits light, the adhesive can reduce or prevent a leakage of lighttransmitted through the tile-shaped microelement from the substrateside.

The semiconductor device includes a plurality of the tile-shapedmicroelements provided on the substrate, one of the tile-shapedmicroelements being preferably a device having a function different fromthe function of the other tile-shaped microelements.

In this case, a semiconductor device including a compact combination ofa plurality of devices having different functions can be formed,although such a semiconductor device cannot be formed by using amonolithic substrate.

In the semiconductor device, the functional film preferably includes aresin film, an inorganic film, or a laminated film including thesefilms.

In this case, a film comprising a material having a desired propertyaccording to the function of the tile-shaped microelement can beappropriately selected and used, thereby improving the function of thetile-shaped microelement.

In the semiconductor device, the functional film preferably has ananti-reflection function.

In this case, a fault, such as noise due to light reflection, can bereduced or prevented.

A method of manufacturing a semiconductor device of the presentinvention includes: forming a semiconductor element on a surface of asemiconductor substrate, separating a functional layer which is asurface layer of the semiconductor substrate and which includes thesemiconductor element, to form a tile-shaped microelement, bonding thetile-shaped element to a surface of another substrate, and forming aninsulating functional film to cover at least a portion of thetile-shaped microelement.

The method of manufacturing the semiconductor device is capable offorming an integrated circuit by bonding the semiconductor element whichis separated in a micro tile-shaped shape to any material.

The tile-shaped microelement can be given the function as an electronicdevice or optical device to form a device having any desired function,and the semiconductor device can be made compact (high density).

Since the insulating functional film is provided to cover at least aportion of the tile-shaped microelement, for example, the functionalfilm can be given the barrier property against oxygen and moisture toreduce or suppress deterioration in the element function, increasing thelifetime of the element.

Also, the semiconductor is completed on the semiconductor substrate andthen separated in the micro tile-shaped shape, and thus thesemiconductor element can be tested and sorted before an integratedcircuit is formed.

In a further aspect of the present invention, a method of manufacturinga semiconductor device includes forming a semiconductor element on asurface of a semiconductor substrate, bonding a film to the surface ofthe semiconductor substrate on which the semiconductor element isformed, separating only a functional layer which is a surface layer ofthe semiconductor substrate and which includes the semiconductorelement, to form a tile-shaped microelement, bonding the tile-shapedelement to a surface of another substrate, and forming an insulatingfunctional film to cover at least a portion of the tile-shapedmicroelement.

The method of manufacturing the semiconductor device is capable ofseparating the functional layer including the semiconductor element in amicro tile shape from the semiconductor substrate, and then mounting thesemiconductor element on a film for permitting handling. Therefore, anydesired semiconductor element can be selected separately and joined to afinal substrate, and the size of the semiconductor element which can behandled can be decreased to a size smaller than that in a related artmounting technique.

The tile-shaped microelement can be given the function as an electronicdevice or optical device to form a device having any desired function,and the semiconductor device can be made compact (high density).

Since the insulating functional film is provided to cover at least aportion of the tile-shaped microelement, for example, the functionalfilm can be given the barrier property against oxygen and moisture toreduce or suppress deterioration in the element function, increasing thelifetime of the element.

Also, the semiconductor is completed on the semiconductor substrate andthen separated in the micro tile shape, and thus the semiconductorelement can be tested and sorted before an integrated circuit is formed.

In the method of manufacturing the semiconductor device, the insulatingfunctional film is preferably formed by a droplet discharge process ordispenser process.

In this case, a material for the functional film can be coated on anydesired portion, and thus can be selectively provided only at anydesired position of the substrate. Also, the amount of the material usedfor the functional film can be significantly decreased to decrease themanufacture cost.

In the method of manufacturing the semiconductor device, thesemiconductor element in the tile-shaped microelement bonded to theother substrate is preferably bonded to a circuit formed on the othersubstrate.

In this case, the semiconductor layer in the functional layer iselectrically connected to a circuit formed on the other substrate toform a semiconductor device having multiple functions.

An electro-optic device of the present invention includes theabove-described semiconductor device or a semiconductor devicemanufactured by the above-described manufacturing method.

The electro-optic device can be made compact (high density), and hashigher reliability because it includes the semiconductor device in whichdeterioration in the element function is reduced or suppressed.

An electronic apparatus of the present invention includes theabove-described electro-optic device.

The electronic apparatus has higher reliability because it includes theelectro-optic device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side view illustrating a significant portion ofthe schematic construction of a semiconductor device according to anexemplary embodiment of the present invention.

FIG. 2 is a sectional side view illustrating a significant portion ofthe schematic construction of a surface emitting laser formed in atile-shaped microelement.

FIG. 3 is a schematic illustrating the current path in the surfaceemitting laser shown in FIG. 2.

FIG. 4 is a sectional side view illustrating a significant portion ofthe schematic construction of a semiconductor device according toanother exemplary embodiment of the present invention.

FIG. 5 is a sectional side view illustrating a significant portion ofthe schematic construction of a semiconductor device according to amodified exemplary embodiment of the semiconductor device shown in FIG.4.

FIG. 6 is a sectional side view illustrating a significant portion in afirst step of an example of a method of manufacturing a semiconductordevice according to the present invention.

FIG. 7 is a sectional side view illustrating a significant portion in asecond step of the example of the manufacturing method.

FIG. 8 is a sectional side view illustrating a significant portion in athird step of the example of the manufacturing method.

FIG. 9 is a sectional side view illustrating a significant portion in afourth step of the example of the manufacturing method.

FIG. 10 is a sectional side view illustrating a significant portion in afifth step of the example of the manufacturing method.

FIG. 11 is a sectional side view illustrating a significant portion in asixth step of the example of the manufacturing method.

FIG. 12 is a sectional side view illustrating a significant portion in aseventh step of the example of the manufacturing method.

FIG. 13 is a sectional side view illustrating a significant portion inan eighth step of the example of the manufacturing method.

FIG. 14 is a sectional side view illustrating a significant portion in aninth step of the example of the manufacturing method.

FIG. 15 is a sectional side view illustrating a significant portion inan eleventh step of the example of the manufacturing method.

FIG. 16 is a schematic showing an example in which an electronicapparatus including an electro-optic device of the present invention isapplied to a cellular phone.

FIG. 17 is a schematic showing an example in which an electronicapparatus including an electro-optic device of the present invention isapplied to a wristwatch-type electronic apparatus.

FIG. 18 is a schematic showing an example in which an electronicapparatus including an electro-optic device of the present invention isapplied to a portable information processor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A semiconductor device according to the present invention is describedbelow with reference to the drawings.

First Exemplary Embodiment

FIG. 1 is a schematic showing a semiconductor device according to afirst exemplary embodiment of the present invention. The semiconductordevice includes a substrate 10, a tile-shaped microelement 1, and afunctional film 12 covering the tile-shaped element 1. In this exemplaryembodiment, a surface emitting semiconductor laser is formed as thesemiconductor device.

The tile-shaped microelement 1 has a micro tile shape (a substantiallyplate shape) having a semiconductor device (semiconductor element)formed therein, and includes a surface emitting laser having astructure, for example, shown in FIG. 2.

The surface emitting laser includes a highly conductive layer (highcarrier concentration layer) 52 b including an n-type gallium arsenidecompound semiconductor layer (n-type GaAs layer) having a rectangularplanar shape, a lower reflecting mirror layer structure (hereinafter“lower mirror”) 52 a formed over the entire upper surface of the highlyconductive layer 52 b, and layers 53 a to 53 f which are laminated onthe lower mirror 52 a in that order to form a cylindrical mesa. Also, aninsulating layer 54 made of polyimide or the like and electrodes 53 gand 53 h are properly provided around the mesa. The tile-shapedmicroelement 1 including the surface emitting laser includes asemiconductor element 53 including the layers 53 a to 53 h, and thelower mirror 52 a.

In the present invention, the tile-shaped microelement 1 has an elementstructure necessary to exhibit at least a desired function as asemiconductor element. For example, when the function as the surfaceemitting laser is exhibited, the tile-shaped microelement 1 has asemiconductor layer structure including at least the upper and lowermirrors 53 e and 52 a and the layers held between both mirror layers.However, the tile-shaped microelement 1 may include secondary componentsto exhibit the function, such as the contact layer 53 f, the electrodes53 g and 53 h, and the insulating layer 54. A portion including thetile-shaped microelement 1, the functional layer 12 and the high carrierconcentration layer 52 b is referred to as a “semiconductor elementmember 500”. The mesa may have any desired shape.

The mesa includes the following structure. The n-type clad layer 53 aincluding n-type Al_(0.5)Ga_(0.5)As formed on the lower mirror 52 a, andthe active layer 53 b and the p-type clad layer 53 c including p-typeAl_(0.5)Ga_(0.5)As are formed on the n-type clad layer 53 a. Also, thehorizontal oxide layer (current aperture) 53 d formed in a ring in theperiphery of the mesa, and the upper reflecting mirror layer structure(hereinafter “upper mirror”) 53 e and the contact layer 53 f including ap-type GaAs layer are further formed in that order. Furthermore, theinsulating layer 54 is formed around the mesa, the p-type (cathode)electrode 53 g and n-type (anode) electrode 53 h are formed on the uppersurfaces of the contact layer 53 f and the lower mirror 52 a,respectively. Therefore, when a voltage is applied between bothelectrodes, a laser beam is emitted from the upper end of the mesa inthe axial direction thereof. The cathode electrode 53 g is formed in aring so that the laser beam is emitted from the center of the mesa.

The highly conductive layer 52 b is adapted to secure a current path todecrease the electric resistance of the semiconductor element. Thehighly conductive layer 52 b comprises a high carrier concentrationlayer of the same conduction type as the lower mirror 52 a, and has acarrier concentration of about 5 to 10×10¹⁸ cm⁻³. Although the highcarrier concentration layer is preferably a GaAs layer, it may be anAl_(x)Ga_(1-x)As layer (x is 0.2 or less). However, in theAl_(x)Ga_(1-x)As layer, the resistance tends to increase as x increases.The thickness of the highly conductive layer 52 b is 0.3 μm or more, andpreferably 1 μm or more.

The active layer 53 b includes a GaAs well layer and anAl_(0.3)Ga_(0.7)As barrier layer, the well layer having a multiquantumwell structure (MQW) including three layers.

Each of the mirrors 52 a and 53 e constitutes a resonator serving as alaser reflecting mirror, and, for example, it is a distributed Braggreflection multilayer film mirror (DBR mirror) in which two types ofAl_(x)Ga_(1-x)As layers having different compositions are alternatelylaminated. In this exemplary embodiment, the lower mirror 52 a comprisesabout 30 pairs of n-type Al_(0.15)Ga_(0.85)As layer and n-typeAl_(0.9)Ga_(0.1)As layer which are alternately laminated, and the uppermirror 53 e comprises about 25 pairs of p-type Al_(0.15)Ga_(0.85)Aslayer and p-type Al_(0.9)Ga_(0.1)As layer which are alternatelylaminated. Each of the Al_(x)Ga_(1-x)As layers has an optical thicknesscorresponding to ¼ of the laser emission wavelength, and a carrierconcentration of about 1 to 5×10¹⁸ cm⁻³. The upper mirror 53 e is dopedwith C (carbon) to be made the p-type, and the lower mirror 52 a isdoped with Si to be made the n-type. Therefore, the upper mirror 53 e,the active layer 53 b undoped with an impurity and the lower mirror 52 aconstitute a PIN diode. The conduction types of the lower and uppermirrors may be reversed according to the polarity of the laser. Also, adielectric multilayer film or metal film may be formed instead of thesemiconductor multilayer film.

The current aperture 53 d is an insulating layer mainly including an Aloxide, and has the effect of decreasing the area of an active region toemit light to decrease the threshold current and narrow the beam width.

The surface emitting laser having the above-described element structurehas such a current path as shown in FIG. 3.

In FIG. 3, the resistance R3 of the upper mirror 53 e, the resistance R1of the lower mirror 52 a and the resistance R2 of the high carrierconcentration layer 53 b are connected to each other to form an electriccircuit between the electrodes 53 g and 53 h, and a current possiblyflows in the circuit. The resistances R1 and R2 are connected inparallel, and thus if the resistances R1 and R2 are considered as atotal resistance R, the resistances R and R3 are connected in series inthe electric circuit.

In this exemplary embodiment, the resistivity of the lower mirror 52 ais about 1.1×10⁻² Ωcm (the DBR mirror including 30 pairs of layers andhaving a carrier concentration of 5×10¹⁸ cm⁻³), and thus R1=20Ω when thethickness is 3 μm. On the other hand, in this exemplary embodiment, theresistivity of the high carrier concentration layer is about 1.3×10⁻³Ωcm (the n-GaAs layer having a carrier concentration of 1×10¹⁹ cm⁻³),and thus R2=6.7Ω when the thickness is 1 μm, and R2=3.35Ω when thethickness is 2 μm. As described above, the resistances R1 and R2 areconnected in parallel, and thus the total resistance R=5.0Ω when thethickness of the high carrier concentration layer is 1 μm, and R=2.9Ωwhen the thickness of the high carrier concentration layer is 2 μm.These values are ¼ to ⅙ of that of a single lower mirror without thehigh carrier concentration layer, and thus the electric resistance ofthe surface emitting laser can be decreased.

When the carrier concentration of the lower mirror 52 a is increased toabout 1×10¹⁹ cm⁻³ to impart conductivity to the lower mirror 52 a, anoptical absorption loss is increased to deteriorate the function(optical property) as a reflecting layer. In this exemplary embodiment,therefore, the high carrier concentration layer which has highconductivity and a high optical-absorption coefficient and which thushas the influence on the optical property is provided below (a portionapart from the light emission path of the laser beam) the lower mirroras viewed from the active layer, thereby preventing the influence of thelaser on the optical property.

The position of the highly conductive layer may be appropriately setaccording to the influence on the properties of the semiconductorelement, and the position is not limited to the above-describedposition. For example, the highly conductive layer may be inserted intothe functional layer.

The thickness of the tile-shaped microelement 1 is, for example, about 1μm to 10 (20) μm. The semiconductor device (semiconductor element) isformed in the tile-shaped microelement 1. Besides the surface emittinglaser (VCSEL), a light emitting diode (LED), a photodiode (PD), a highelectron mobility transistor (HEMT), a hetero bipolar transistor (HBT),or the like can be formed as the semiconductor device. Any one of thesesemiconductor devices includes a plurality of epitaxial layers laminatedon a predetermined substrate. Each of the semiconductor devices furtherincludes electrodes, and is subjected to an operation test.

The tile-shaped microelement 1 is separated in a predetermined shapefrom the substrate by the method described below. The size (length andwidth) of the tile-shaped microelement 1 is, for example, several tenspm to several hundreds μm.

The tile-shaped microelement 1 is bonded to a substrate 10 other thanthe substrate used to manufacture the tile-shaped microelement 1 to forma semiconductor device, such as OEIC or the like. Namely, as shown inFIGS. 1 and 2, the tile-shaped microelement 1 is bonded to the Sisubstrate 10 with an adhesive layer 11. Also, a cathode electrode 61 andanode electrode 62 are formed on the surface of the substrate 10 so asto be connected to a circuit (not shown in the drawings) previouslyformed thereon. Furthermore, the electrode 61 is connected to theelectrode 53 g through wiring 64 formed on the surface of an insulatinglayer 63, and the electrode 62 is connected to the electrode 53 hthrough wiring 65 formed on the surface of the insulating layer 63.

As an adhesive to form the adhesive layer 11, an insulating resin ispreferably used. The insulating adhesive layer 11 exhibits insulatingperformance together with the insulating layer 63, thereby securelypreventing a short circuit in the wirings 64 and 65. In this exemplaryembodiment, as described above, the surface emitting laser of thetile-shaped microelement 1 emits light to the side opposite to thesubstrate 10, and thus the adhesive is preferably non-transmissive tovisible light and infrared light. In this case, even when thetile-shaped microelement 1 is thin and thus likely to transmit light tothe side opposite to the emission side, the adhesive can prevent aleakage of the light transmitted through the tile-shaped microelement 1from the substrate 10 side.

Preferred examples of the insulating adhesive include ultraviolet curingresins such as acrylic resins, epoxy resins, melamine resins, polyimideresins, and the like, and heat curing resins. Also, a two-liquid mixingcuring epoxy resin can be used as a chemical reaction curing type.

Although the adhesives including these resins have slight differences inlight transmittance, they are substantially transparent, i.e.,light-transmissive. Therefore, a black pigment or black dye, such ascarbon black or the like, is added to the resin to decreasetransmittance, thereby making the resin non-transmissive (lightabsorptive). The insulating performance decreases as the amount of thecarbon black added increases. In this case, two layers including anadhesive layer containing carbon black and an adhesive layer notcontaining carbon black may be laminated by coating according to demand.

As shown in FIG. 1, the tile-shaped microelement 1 bonded to thesubstrate 10 is coated with the insulating functional film 12 togetherwith the wirings 64 and 65. The functional film 12 is formed to have afunction (property) according to the function of the semiconductorelement in the tile-shaped microelement 1, and includes a resin film, aninorganic film, or a laminated film including these films.

In this exemplary embodiment, the functional film 12 is provided tocover and seal the entire tile-shaped microelement 1, and functions as aprotective film. Namely, the functional film 12 has a barrier propertyagainst oxygen and moisture, and thus can prevent the progress ofdeterioration of the surface emitting laser in the tile-shapedmicroelement 1 due to oxygen and moisture.

As a material to form the functional film 12 having the barrier propertyagainst oxygen and moisture, the above-described resin material orinorganic material is used. Particularly, the resin material, such as anacrylic resin, an epoxy resin, a melamine resin, a polyimide resin, orthe like is preferably used. Since the functional film 12 covers thelight emission side of the surface emitting laser in the tile-shapedmicroelement 1, the functional film 12 is transmissive to visible lightand infrared light. As described above, each of the above resins istransmissive to light and thus can be used for the transmissivefunctional film 12 of this exemplary embodiment without the addition ofthe black pigment or the like, unlike in the formation of the adhesivelayer 11.

Various types of films can be used as the functional film 12 accordingto the function of the semiconductor element (semiconductor device) inthe tile-shaped microelement 1, and various materials can also be used.

For example, the semiconductor element (semiconductor device) can beformed and used as various devices (not shown) other than the surfaceemitting laser, for example, a light emitting element (light emittingdiode), a light receiving element (photodiode), a transistor, a diode,and the like. With respect to an operation state, for example, the lightemitting element or light receiving element can be used in a state inwhich its light emitting section or light receiving section faces thesubstrate 10 side or the side opposite to the substrate 10, or faces inthe planar direction of the substrate 10. In this case, the functionalfilm 12 transmissive to visible light and infrared light is preferablyused for the light emitting section or light receiving section of thelight emitting element or light receiving element, and the side oppositeto the light emitting section or light receiving section is preferablycoated with a film non-transmissive to visible light and infrared light.

When the functional film 12 is provided for partial protection andinsulation, the entire region of the tile-shaped microelement 1 is notcoated, but only a principal portion, for example, the light emittingsection or light receiving section of the light emitting element oflight receiving element, may be coated, or only the wiring portion maybe coated.

Besides the resin materials, oxides and nitride, such as SiOx, SiN, AlN,AlOx, ZrOx, ZnOx, TiOx, TaOx, Y₂O₃, and the like, and inorganicmaterials, such as diamond and the like, may be used for the functionalfilm 12. Also, a laminated film of an inorganic material film and aresin material film may be used.

As the method of forming the resin film (the functional film 12), adroplet discharge process (ink jet process), a dispenser process, a spincoating process, a roll coating process, a printing process, or the likecan be used. Particularly, when position selectivity is required, forexample, when the resin film is selectively coated only on the lightemitting section or light receiving section, the droplet dischargeprocess or dispenser process is preferably used. The droplet dischargeprocess or dispenser process is capable of providing the material forthe functional film 12 only at a desired position, and thus thefunctional film 12 can be selectively provided only at a desiredposition of the substrate 10. Also, the amount of the material used forthe functional film 12 can be significantly decreased, therebydecreasing the manufacture cost.

When the functional film 12 includes an inorganic film or diamond film,the functional film 12 can be caused to function as a heat radiatinglayer. Namely, during driving, heat is generated from the semiconductorelement in the tile-shaped microelement 1 to increase the elementtemperature to deteriorate the element properties. However, thefunctional film 12 can radiate heat to reduce or prevent thedeterioration in the element properties.

As the method of forming the inorganic film (the functional film 12), avacuum deposition method, a CVD method, or a method including forming afilm of a precursor (for example, polysilazane when a SiO₂ film isformed) of a material to form the film, and then oxidizing (heating) ornitriding the film to form a desired film can be used.

The functional film 12 may include a laminate of inorganic materialfilms, a laminate of resin material films, or a laminate of an inorganicmaterial film and resin material film. In this case, the functions ofthe respective films are combined to form a film having multiplefunctions.

For example, inorganic material films having different refractiveindexes may be laminated, or an inorganic material film and resinmaterial film may be laminated to form the functional film 12functioning as an anti-reflection film.

Consideration is given to the simplest case in which the single-layeranti-reflection film is formed on a GaAs (refractive index n=3.6)surface. When a film with a refractive index n is formed to a thicknessd=λ/4n, the lowest reflectance can be obtained at wavelength λ. Thereflectance becomes minimum when the refractive index n of the film isclose to the square root 1.89 of the refractive index of 3.6 of GaAs.

Therefore, when yttrium oxide (Y₂O₃; refractive index n=1.87) is used asthe material of the film, and the thickness d is 113.6 nm, thecalculated reflectance at λ=850 nm is 0.5%. Therefore, the film is foundto be the good anti-reflection film.

When zirconia (ZrO₂; refractive index n=2.0) is used as the material ofthe film, and the thickness d is 106.25 nm, the calculated reflectanceat λ=850 nm is 2%. Therefore, the film is also found to sufficientlyfunction as the anti-reflection film.

Also, a metal film may be laminated on the resin material film orinorganic material film to make the transmissive film non-transmissiveand enhance the barrier property against oxygen and moisture.

Besides the silicon semiconductor substrate, a substrate includingquartz glass, sapphire, a metal, a ceramic or plastic film may be usedas the substrate 10. When the substrate 10 includes a siliconsemiconductor, the substrate 10 may be used for CCD (charge coupleddevice). When the substrate 10 includes glass, such as quartz or thelike, the substrate 10 can be used for a display, such as a liquidcrystal display (LCD), an organic EL device, or the like. When thesubstrate 10 includes a plastic film, the substrate 10 can be used for aliquid crystal display, an organic electroluminescence panel, an IC filmpackage or the like.

Furthermore, a plurality of the tile-shaped microelements 1 may beprovided on the substrate 10. In this case, one of the tile-shapedmicroelements 1 preferably includes a device having a function differentfrom the functions of the other tile-shaped microelements 1.

Examples of a combination of the tile-shaped microelements 1 include thefollowing:

(1) One of the tile-shaped microelement 1 includes a light emittingelement, and the other tile-shaped microelements 1 include lightreceiving elements.

(2) One of the tile-shaped microelement 1 includes a light emittingelement emitting light at a wavelength λ₁, and the other tile-shapedmicroelements 1 include light emitting elements emitting light at awavelength λ₂.

(3) One of the tile-shaped microelement 1 includes a light receivingelement detecting light at a wavelength λ₁, and the other tile-shapedmicroelements 1 include light receiving elements detecting light at awavelength λ₂.

(4) One of the tile-shaped microelement 1 includes a transistor, and theother tile-shaped microelements 1 include diodes.

Herein, examples of the light emitting element include theabove-described gallium arsenide surface emitting laser (VCSEL), aphotodiode (PD), and the like. Examples of the transistor include a highelectron mobility transistor (HEMT), and the like. The semiconductorelement (semiconductor device) provided in the tile-shaped microelement1 may include a resistor or capacitor, or only the resistor or capacitormay be formed as the semiconductor device.

Second Exemplary Embodiment

FIG. 4 is a schematic showing a semiconductor device according to asecond exemplary embodiment of the present invention. Particularly, thesemiconductor device includes two types of tile-shaped microelements 1which are superposed.

Namely, the semiconductor device shown in FIG. 4 includes a tile-shapedmicroelement 1 a including a surface emitting laser 21 and a tile-shapedmicroelement 1 b including a photodiode 22, both of which are providedon a transparent substrate 10 a, and a functional film 30 covering theseelements.

Each of adhesive layers 11 a and 11 b for respectively bonding thetile-shaped microelement 1 a and the tile-shaped microelement 1 b to thesubstrate 10 a has transparency and insulation performance. The adhesivelayer 11 b to bond together the tile-shaped microelement 1 a and thetile-shaped microelement 1 b also serves as a functional film to coverand protect the tile-shaped microelement 1 a. The functional film 30comprises a non-transmissive material, i.e., the above-described resinmaterial containing a black pigment, such as carbon black or the like.

In this exemplary embodiment, the surface emitting laser 21 of thetile-shaped microelement 1 a emits a laser beam (wavelength λ₀) towardthe substrate 10 a, and also emits a laser beam (wavelength λ₀) towardthe tile-shaped microelement 1 b. The photodiode 22 of the tile-shapedmicroelement 1 b is disposed on the emission axis of the surfaceemitting laser 21. Therefore, the laser beam (wavelength λ₀) emitted tothe tile-shaped microelement 1 b is incident on the photodiode 22 sothat the output (emission amount) of the laser beam (wavelength λ₀)emitted from the surface emitting laser 21 is detected by the photodiode22.

On the other hand, the laser beam (wavelength λ₀) emitted to thesubstrate 10 a is transmitted through the transparent substrate 10 a andis used as a communication signal or the like.

The laser beam (wavelength λ₀) emitted from the surface emitting laser21 of the tile-shaped microelement 1 a and incident on the photodiode 22of the tile-shaped microelement 1 b is transmitted through thetile-shaped microelement 1 b and absorbed by the non-transmissivefunctional film 30, thereby reducing or preventing a leakage to theoutside. Therefore, stray light due to the laser beam transmittedthrough the tile-shaped microelement 1 b can be significantly decreased,and noise due to feedback light can be decreased.

FIG. 5 shows a modified exemplary embodiment of the semiconductor deviceshown in FIG. 4. The semiconductor device shown in FIG. 5 is differentfrom the semiconductor device shown in FIG. 4 in that the positions ofthe tile-shaped microelements 1 a and 1 b are reversed vertically, inthat each of the surface emitting laser 21 and the photodiode 22provided on the tile-shaped microelements 1 a and 1 b, respectively,faces the side opposite to that in FIG. 4, in that the upper surface ofthe tile-shaped microelement 1 a including the surface emitting laser 21is covered with a transmissive functional film 31, in that thetile-shaped microelement 1 b is bonded to the substrate 10 a with anadhesive layer 11 c comprising a non-transmissive adhesive, and in thatanti-reflection layers 41 and 42 are provided at the top and bottom ofthe substrate 10 a. When the substrate 10 a includes a non-transparentmember, the anti-reflection layer need not be provided at the bottom ofthe substrate 10 a. Instead of the anti-reflection layer 42 provided atthe bottom of the substrate 10 a, a light absorbing layer may beprovided at the bottom of the substrate 10 a. The functional film 31includes a light-transmissive material, i.e., the above-describedlight-transmissive resin material or inorganic material.

Therefore, in the semiconductor device of this exemplary embodiment, alaser beam (wavelength λ₀) is emitted upward (upward in the drawing)apart from the substrate 10 a in the direction opposite to that in thesemiconductor device shown in FIG. 4. Like in the semiconductor deviceshown in FIG. 4, stray light due to a laser beam transmitted through thetile-shaped microelement 1 b can be significantly decreased, and noisedue to feedback light can be decreased.

(Exemplary Method of Manufacturing the Tile-Shaped Microelement)

A description is provided below of the method of manufacturing thetile-shaped microelement and the semiconductor device.

In the manufacturing method, a description is provided of a case inwhich a compound semiconductor device (compound semiconductor element)formed as the tile-shaped microelement is bonded to a silicon LSI chipused as a substrate. However, the present invention can be applied toany type of semiconductor device and any type of LSI chip. In thisexemplary embodiment, the “semiconductor substrate” means a substrateincluding a semiconductor material. However, the “semiconductorsubstrate” is not limited to a plate-shaped substrate, and includes anysubstrate including a semiconductor material regardless of the shape.

<First Step>

FIG. 6 is a schematic sectional view showing the first step of themanufacturing method. In FIG. 6, a substrate 110 is a semiconductorsubstrate, for example, a gallium arsenide compound semiconductorsubstrate. A sacrificial layer 111 is provided as a bottom layer on thesubstrate 110. The sacrificial layer 111 includes aluminum arsenide(AlAs) and has a thickness of, for example, several hundreds nm.

For example, a functional layer 112 is provided on the sacrificial layer111. The thickness of the functional layer 112 is, for example, about 1μm to 10 (20) μm. Furthermore, semiconductor devices (semiconductorelements) 113 are formed on the functional layer 112. As thesemiconductor devices 113, for example, light emitting diodes (LED),surface emitting lasers (VCSEL), photodiodes (PD), high electronmobility transistors (HEMT), hetero bipolar transistors (HBT), or thelike can be formed. Any one of these semiconductor devices 113 is formedby laminating a plurality of epitaxial layers on the substrate 110. Eachof the semiconductor devices 113 further comprises an electrode, and issubjected to an operating test.

<Second Step>

FIG. 7 is a schematic sectional view showing the second step of themanufacturing method. In this step, separation grooves 121 are formed toseparate the respective semiconductor devices 113. The separationgrooves 112 have a depth reaching at least the sacrificial layer 111.For example, the width and depth of the separation grooves 121 are 10 μmto several hundreds pm. The separation grooves 121 are connected to eachother without dead ends so that the selective etching solution describedbelow flows through the separation grooves 121. Furthermore, theseparation grooves 121 are preferably formed in a grid-like shape.

The interval of the separation grooves 121 is several tens μm to severalhundreds μm, and thus the size of each of the semiconductor devices 113separated by the separation grooves 121 has an area of several tens μmto several hundreds μm square. The separation grooves 121 are formed bya method including photolithography and wet etching, or a dry etchingmethod. The separation grooves 121 may be formed in U-shaped grooves bydicing in a range causing no crack in the substrate.

<Third Step>

FIG. 8 is a schematic sectional view showing the third step of themanufacturing method. In this step, an intermediate transfer film 131 isbonded to the surface (the semiconductor device 113 side) of thesubstrate 110. The intermediate transfer film 131 is a flexiblestrip-shaped film having a surface coated with an adhesive.

FIG. 9 is a schematic sectional view showing the fourth step of themanufacturing method. In this step, a selective etching solution 141 isinjected into the separation grooves 121. In this step, lowconcentration hydrochloric acid having high selectivity to aluminumarsenide is used as the selective etching solution 141 to selectivelyetch only the sacrificial layer 111.

<Fifth Step>

FIG. 10 is a schematic sectional view showing the fifth step of themanufacturing method. In this step, the sacrificial layer 111 isentirely removed by selective etching after the passage of apredetermined time from the injection of the selective etching solution141 into the separation grooves 121 in the fourth step.

<Sixth Step>

FIG. 11 is a schematic sectional view showing the sixth step of themanufacturing method. After the sacrificial layer 111 is entirely etchedout in the fifth step, the functional layer 112 is separated from thesubstrate 110.

In the sixth step, the intermediate transfer film 131 is separated fromthe substrate 110 to separate the functional film 112 bonded to theintermediate transfer film 131 from the substrate 110.

As a result, the functional film 112 having the semiconductor devices113 formed thereon is divided into predetermined shapes (for example,micro tile shapes) by the separation grooves 121 and etching of thesacrificial layer 111 to form semiconductor elements (the “tile-shapedmicroelements” of each of the above embodiments), the functional film112 being adhered to the intermediate transfer film 131. In this step,the thickness of the functional layer 112 is preferably, for example, 1μm to 8 μm, and the size (width and length) is preferably, for example,several tens μm to several hundreds μm.

<Seventh Step>

FIG. 12 is a schematic sectional view showing the seventh step of themanufacturing method. In this step, the intermediate transfer film 131having the tile-shaped microelements 161 bonded thereto is moved toalign each of the tile-shaped microelements 161 with a desired positionof a final substrate 171 (the substrate 10 or 10 a). The final substrate171 includes, for example, a silicon semiconductor, and a LSI region 172is formed on the final substrate 171. Also, an adhesive 173 is coated onthe desired position of the final substrate 171, to bond the tile-shapedmicroelement 161.

<Eighth Step>

FIG. 13 is a schematic sectional view showing the eighth step of themanufacturing method. In this step, the tile-shaped microelement 161aligned with the desired position of the final substrate 171 is pressedby a collet 181 with the intermediate transfer film 131 providedtherebetween, and is joined to the final substrate 171. Since thedesired position is coated with the adhesive 173, the tile-shapedmicroelement 161 is bonded to the desired position of the finalsubstrate 171.

<Ninth Step>

FIG. 14 is a schematic sectional view showing the ninth step of themanufacturing method. In this step, the adhesive force of theintermediate transfer film 131 is lost to separate the intermediatetransfer film 131 from the tile-shaped microelement 161.

The adhesive of the intermediate transfer film 131 is preferably UVcurable or heat curable. With the UV curable adhesive, the collet 181including a transparent material is used, and an ultraviolet ray (UV) isapplied to the end of the collet 181 to lose the adhesive force of theintermediate transfer film 131. With the heat curable adhesive, thecollet 181 may be heated. Alternatively, the entire surface of theintermediate transfer film 131 may be irradiated with an ultraviolet rayto lose the adhesive force of the entire surface after the sixth step.Although the adhesive force is lost, adhesion actually slightly remainsso that the tile-shaped microelement 161 is held on the intermediatetransfer film 131 because the tile-shaped microelement 161 is thin andlightweight.

<Tenth Step>

This step is not shown in a drawing. In this step, the tile-shapedmicroelement 161 is finally bonded to the final substrate 171 by heatingor the like.

<Eleventh Step>

FIG. 15 is a schematic sectional view showing the eleventh step of themanufacturing method. In this step, the electrode of the tile-shapedmicroelement 161 is electrically connected to the circuit 172 formed onthe final substrate 171 through wiring 191 to complete a semiconductordevice, such as an LSI chip. As the final substrate 171, a glass quartzsubstrate or plastic film as well as the silicon semiconductor may beused.

<Twelfth Step>

In this step, a resin material or inorganic material film is formed onthe tile-shaped microelement 161 formed on the final substrate 171 inthe step shown in FIG. 15 to form a functional film covering at least aportion of the tile-shaped microelement 161, as shown in FIG. 1. Theproperties and shape of the functional film are appropriately selectedaccording to the semiconductor element (semiconductor device) providedin the tile-shaped microelement 161.

When the tile-shaped microelements are superposed, the steps from thefirst step to the twelfth step are repeated. By performing these steps,a plurality of tile-shaped microelements can be simply and rapidlysuperposed on a predetermined substrate.

(Application)

Examples of application of the semiconductor device of the presentinvention are described below.

In a first example of application, the semiconductor device of thesecond exemplary embodiment is used as an optoelectronics integratedcircuit. Namely, like in the second exemplary embodiment, a lightemitting element (surface emitting laser) and a light receiving element(photodiode) are superposed, and an APC circuit is also provided to forman integrated circuit comprising an optical output device. A pluralityof light emitting elements having different emission wavelengths may besuperposed to form an integrated circuit including an emission means(output device). Alternatively, a plurality of light receiving elementsselectively detecting lights at different wavelengths may be superposedto form an integrated circuit including a receiving device (inputdevice).

By using any of these integrated circuits, for example, a computer isformed. Although an electric signal is used for signal processing in theintegrated circuit constituting a CPU, an optical input/output device isused in a bus to transmit data between the CPU and a storage device.

In this example of application, the signal transfer speed of the bus,which is a bottleneck of the processing speed of the computer, can besignificantly increased, as compared with a related art computer.

In this example of application, the tile-shaped microelements aresuperposed, and thus the computer can be significantly miniaturized.

In this example of application, when a surface emitting laser with anAPC circuit is used for the input/output device constituting the bus, ahigh-performance state can be stably maintained over a long period oftime.

In a second example of application, instead of a thin film transistor(TFT) generally used as a driving transistor, a resistor, a capacitor orthe like, a silicon transistor, a resistor or a capacitor formed in thetile-shaped microelement is used for each pixel of an electro-opticdevice, such as a liquid crystal display, a plasma display or an organicEL (Electroluminescence) display to form a semiconductor device.

In this example of application, a high-performance switching functioncan be achieved as compared with the use of the TFT, and anelectro-optic device capable of changing display states at a high speedcan be provided.

(Exemplary Electronic Apparatus)

Examples of an electronic apparatus including the semiconductor deviceand electro-optic device of any one of the exemplary embodiments aredescribed below.

FIG. 16 is a perspective view showing an example of a cellular phone. InFIG. 16, reference numeral 1000 denotes a cellular phone body includingthe semiconductor device, and reference numeral 1001 denotes a displaysection comprising the electro-optic device.

FIG. 17 is a perspective view showing an example of a wristwatch-typeelectronic apparatus. In FIG. 17, reference numeral 1100 denotes a watchbody including the semiconductor device, and reference numeral 1101denotes a display section including the electro-optic device.

FIG. 18 is a perspective view showing an example of portable informationprocessors, such as a word processor, a personal computer, and the like.In FIG. 18, reference numeral 1200 denotes an information processor,reference numeral 1202 denotes an input section such as a key board orthe like, reference numeral 1204 denotes an information processor bodyincluding the semiconductor device, and reference numeral 1206 denotes adisplay section including the electro-optic device.

Each of the electronic apparatuses shown in FIGS. 16 to 18 includes thesemiconductor device and the electro-optic device of any one of theexemplary embodiments, and thus an electronic apparatus including adisplay section having high display quality, particularly a brightscreen with high responsiveness, can be realized. By using thesemiconductor device of any of the exemplary embodiments, an electronicapparatus can be miniaturized as compared with a related art apparatus.Furthermore, by using the semiconductor device of any of the exemplaryembodiments, the manufacturing cost can be decreased as compared with arelated art apparatus.

The present invention is not limited to the above-described exemplaryembodiments, and various changes can be made within the scope of thegist of the present invention. For example, the materials and layerstructures of the above embodiments are only examples, and a properchange can be made.

In the exemplary embodiments, a semiconductor device includes aplurality of superposed tile-shaped microelements having differentfunctions. However, the present invention is not limited to theexemplary embodiments, and the tile-shaped microelements may beseparately disposed on a substrate.

[Advantages]

As described above, in the present invention, an insulating functionalfilm is provided to cover at least a portion of a tile-shapedmicroelement. Therefore, for example, when the functional film is givena barrier property against oxygen and moisture, deterioration in theelement function can be reduced or suppressed to increase the lifetimeof the element, thereby enhancing reliability.

1. A method of manufacturing a semiconductor device, comprising: forminga sacrificial layer on a substrate; forming a functional layer on thesacrificial layer; forming a semiconductor element including at least apart of the functional layer; forming a tile-shaped microelement byseparating the semiconductor element from the substrate by etching thesacrificial layer; bonding the tile-shaped element to another substrate;forming an insulating protective film so as to cover at least a portionof the tile-shaped microelement; and electrically connecting thesemiconductor element to a circuit previously formed.
 2. The method ofmanufacturing the semiconductor device according to claim 1, furtherincluding forming the functional film by at least one of a dropletdischarge process and a dispenser process.
 3. An electro-optic device,comprising: a semiconductor device manufactured by the method ofclaim
 1. 4. A method of manufacturing a semiconductor device,comprising: forming a sacrificial layer on a substrate; forming afunctional layer on the sacrificial layer; forming a semiconductorelement including at least a part of the functional layer; etching thesacrificial layer to separate the semiconductor element from thesubstrate and form a tile-shaped microelement; bonding the tile-shapedmicroelement to another substrate; electrically connecting thetile-shaped microelement to a circuit previously formed; and forming aninsulating protective film having a barrier property against oxygen andmoisture so as to cover at least a portion of the tile-shapedmicroelement.
 5. A method of manufacturing a semiconductor device thatcomprises a substrate; a tile-shaped microelement bonded to thesubstrate; and an insulating protective film having a barrier propertyagainst oxygen and moisture, the insulating protective film provided tocover at least a portion of the tile-shaped microelement, in which thefunctional film covers the tile-shaped microelement in a sealed state,the method comprising: forming a sacrificial layer on a substrate;forming a functional layer on the sacrificial layer; forming asemiconductor element including at least a part of the functional layer;forming a tile-shaped microelement by separating the semiconductorelement from the substrate by etching the sacrificial layer; bonding thetile-shaped element to another substrate; forming an insulatingprotective film so as to cover at least a portion of the tile-shapedmicroelement; and electrically connecting the semiconductor element to acircuit previously formed.